The present invention relates to a water-in-oil type emulsified fuel oil in which water is dispersed in heavy oil and more particularly relates to a water-in-oil type emulsified fuel oil which can contribute to energy-saving and reduction in discharge of carbon dioxide for inhibiting global warming.
An emulsified fuel oil containing water in the form of fine particles dispersed in heavy oil has conventionally come to public notice and has been tested since such an emulsified fuel oil has an effect on saving of combustion costs of heavy oil, decrease in NOx and SOx in combustion exhaust gas, and the like. In addition, in recent years, reduction in discharge of carbon dioxide (CO2) has become urgent business also in combustion of fuel oil based on view points of energy-saving and prevention of global warming.
As a conventional production method of emulsified fuel oil, there has been proposed a method in which water is dispersed in heavy oil using a surface active agent as an emulsifier. As emulsification methods, there have been known a method by a static mixer, a method in which water is jetted out into oil, a method by mechanical agitation, a method by a supersonic wave, etc.
When a surface active agent is used as an emulsifier, emulsification is simple. However, water tends to separate partially in emulsified fuel oil during a heating storage. If separated water is generated, it defectively causes a trouble at the time when such an emulsified fuel oil is subjected to combustion. Therefore, emulsified fuel oil has been put in practical use only tentatively in the past though many studies on emulsified fuel oil have been made. In addition, a ratio of water to be added is at most 10%, and generally less than or equal to several %, and it has not been tried to use a quantity more than this because a trouble is prone to be caused. Therefore, an economic effect of energy-saving was not able to be expected very much.
Further, as for heavy oil, there are various kinds of heavy oil such as A heavy oil, B heavy oil, C heavy oil and heavy residue oil containing asphaltene, heavy metals, resins in affluence. However, there has recently been a strong request that only C heavy oil and heavy oil such as the residue oil which is heavier than C heavy oil is intended for combustion with boilers or the like, and the other kinds of heavy oil should be used for other uses.
However, in the case that C heavy oil and heavy oil such as heavy residue oil heavier than C heavy oil is subjected to the above conventional method in which dispersion is performed using water and a surface active agent, and a tendency of separation of water and heavy oil becomes further strong, and the practical use has been extremely difficult.
In view of the aforementioned situation, the present inventor proposed a production method of an emulsified fuel oil in which water having a carbon component dispersed therein is dispersed and emulsified in heavy oil in order to improve the above conventional emulsified fuel oil (See JP-A 6-145675).
The object of the present invention is to provide an emulsified fuel oil having further improved uniform dispersibility of waterdrops, combustion efficiency, reduction in discharge of carbon dioxide, and the like, in comparison with such conventional art. More specifically, the present invention provides an emulsified fuel oil having good combustion efficiency and capable of reducing discharge of carbon dioxide as well, and the emulsification-dispersion of water to heavy oil is easy and secure, and the emulsified fuel oil to be produced is stable for a long term without causing water to separate, isolate, or the like, and can contain water abundantly in comparison with the conventional one.
According to the present invention, there is provided a water-in-oil type emulsion fuel oil, prepared by dispersing and emulsifying in a heavy oil a water/carbon mixture prepared by dispersion carbon fine particles in water with a dispersant and a protective colloid, the emulsion fuel comprising 100 vol % of a heavy oil and 20 to 45 vol % of the water/carbon mixture, the water being uniformly dispersed and emulsified in the heavy oil in the form of particles having diameters of from more than 20 xcexcm to 35 xcexcm, and when the amount of the water/carbon mixture to be mixed with 100 vol % of the heavy oil is 20 to 35 vol %, the dispersed water particles have diameters ranging from 25 to 35 xcexcm, while when the amount is 35 to 45 vol %, they have diameters of from more than 20 xcexcm to 25 xcexcm.